Building an Adirondack Guideboat-Talking tacks

I am now fully aware of what holds a traditionally built Adirondack guideboat together. It may not be what first comes to mind. I am often asked at the Museum if a guideboat is glued together. When I say “No, no glue or adhesives are used in building a traditional guideboat” there is often a puzzled look on the questioner’s face. How can that be? We are so used to modern adhesives, epoxies and such, that make our life so much easier.

Back 160 years ago there were no epoxies. Guideboat builders could not depend on the glues available back then to withstand the rigors of immersion in water for hours. So they devised another way to tightly join the feather laps in their boats; tacks. They simply drove lines of tacks spaced closely together along the lap joint and then clinched them (drove them against a backing iron so that they would bend back on themselves and form a sort of rivet). They drove staggered double rows, one row from the outside of the hull toward the inside and one row from the inside to the outside.

Tacks were easy to obtain back then. Making shoes alone took large quantities. That’s not the case today. Today the only supplier of tacks that I know is John Wilson, who makes oval Shaker boxes. Thank goodness these boxes require tacks otherwise traditional guideboat building may not be possible today. John sells annealed copper tacks of various sizes from very small ones to ones that are quite large. I was only interested in two sizes; No. 2 and No. 2 1/2 for building my boat. The difference between the two sizes is:

No. 2-length 1/4″, head dia. 1/8″ count per oz.-375/oz.

No. 2 1/2 length 5/16″ head dia. 3/16″ count per oz.- 200/oz.

Two tack sizes, No. 2 (right) and No. 2 1/2

Generally you want the tack length to be 1/16 longer than the thickness of the planking so that it clinches nicely. In my case the planking was a little thicker than 3/16″ so I chose the No. 2 1/2 size tacks. The tack head when using this size shows off well when you have row upon row of them on the hull. As I think Joe Namath said “When you got it flaunt it”. But I did add some extra weight to the hull, about 10 oz. , than if I had used No. 2 tacks. I don’t think I’ll notice the extra weight.

John is an old fashioned trusting guy. When you order from him he will send you the goods with no prepayment. He says “Just send me the amount on the invoice when the tacks arrive”.

You’ll need some special tools to drive and clinch annealed copper tacks.You need to start by opening a pilot hole using an awl. Since these tacks have a triangular cross section it is good to use an awl that also has a triangular cross section.

Close up of annealed copper tacks showing triangular cross section of shaft.

The tacks then have to be “stuck” into the pilot hole. This is a tedious task and one that the old time builders with families employed their kids to help them with. I am told that a kid would get the princely sum of 5 cents a round of planking to stick tacks. To give some perspective, there are a total of 3972 tacks in the boat I am now building.

You will need a tack hammer and a clinching iron too. You can use a clinching iron made of iron but iron leaves black smudges on the wood wherever it touches the planking. It is better to pay the extra money for one made of bronze, which doesn’t leave smudges.

Tools for driving and clinching tacks.

At the top of the photo is a make shift clinching iron made from a slick that has had its handle removed. It is great for getting into tight spots. Its use will come up again.